The plans for the 5 MW incorporate several new features. The drive train is a hybrid of conventional and direct drive technology, Aerodyn says. With the offshore market in mind, the aim is to do away with both the maintenance requirements of three stage gear boxes and the vulnerability to saline corrosion of the ring generator on gearless turbines. Aerodyn has chosen a one-stage planetary gear combined with a low revolution generator. The company says this allows the sensitive generator windings to be fully encapsulated.
The yaw system is located within the tower: a system of four hydraulic cylinders and two gear jaws, interlocking with a toothed ring fixed on the inside of the tower, brings the necessary forces to bear without movements that could create wear, the company says. The design also places the rotor bearings directly above the tower opening so that loads are placed directly on the tower. As a result the specific tower head weight is just 31 kg/kW -- the "lowest ever reached in this size of turbine," according to Aerodyn. Another feature is the a sea water heat exchanger at the base of the tower for cooling the generator and gear.